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ix                       HORNS AS A SEXUAL CHARACTER                    2OI
same os cornu, which may however be branched, but which is in
the same way covered by a layer of modified integument; this is
known as the " velvet" ; it only lasts for a certain period, and is
then torn off by the exertions of the animal itself, leaving behind
the bony core, which is popularly termed the horn. It will be clear
that here is only a difference of comparative unimportance ; the
same essential features are present in both groups of animals, but
the modification of the epidermis has progressed along different-
lines. Both can be referred back to the primitive conditions seen
in the paired horns of the Giraffe. Even the difference, such as it
is, is bridged over by the Antelope -Antilocapra, where the os cornu
is bifid and the horn is periodically shed, as is the velvet of the
stag; but in the stag the bony part of the horn is also shed, a
state of affairs which has no parallel in the Hollow-horned
Huminants. The great SivatJieriuin may conceivably be an
annectant form between the two types of compound horns, i.e.
those of the Antelope and those of the Deer. This creature had
two pairs of horns, of which, naturally, only the bony cores remain ;
the hinder pair of these were branched. But although so far they
resemble the Deer's horns rather than the Antelope's, Dr. Murie
has thought that they were covered by a horny sheath and not by
soft skin as in the Deer. In any case these horns were apparently
never shed, which .is a point of likeness with the Antelope and of
difference from the Deer. Apart therefore from the nature of the
covering of the bony cores, there are good grounds for looking
upon them as intermediate between those of the Deer and those
of the Antelopes.
The horns of the Huminants are frequently a secondary sexual
character ; this is especially the case with the Deer. The Rein-
deer is, however, an exception, both the stags and the does
having horns. That they are associated with the reproductive
function is shown by their being shed after the period of rut,
the destruction of the velvet at that period, and also by the effect
upon the horns which any injury to the reproductive glands
produces. Some useful facts upon this latter head have been
amassed by Dr. Gr. H. Fowler,1 who noticed in a series of stags,
horns showing various degrees of degeneration in the antlers pro-
duced by varying degrees and periods of gelding, From the facts
1  " 3Sfotes on some Specimens of Antlers of the Fallow I>eİr, etc. ,'* JProc. Zool. <Sfo*e.
1894, p. 485.